1. Field of the Invention
The present invention relates to an electrically powered, tankless, demand responsive water heater.
2. Description of the Prior Art
Electrically operated water heaters generally are known in the prior art, and include many common features. Many of these are directed to tankless, or instantaneous, type heaters for heating water only when hot water is demanded. Energy saving benefits of such an arrangement are sufficiently discussed in the prior art, and will not be repeated herein. Examples of these patents which illustrate features relevant to the present invention include in U.S. Pat. Nos. 3,351,739, issued to Hanford L. Eckman on Nov. 7, 1967; 3,795,789, issued to Tulio Malzoni et al. on Mar. 5, 1974; 4,459,465, issued on Jul. 10, 1984 to Earl J. Knight; 4,567,350, issued on Jan. 28, 1986 to Alvin E. Todd, Jr.; 4,604,515, issued to Hal Davidson on Aug. 5, 1986; 4,638,147, issued to Anthony Dytch et al. on Jan. 20, 1987; 5,020,127, issued on May 28, 1991, to Harry Eddas et al.; 5,129,034, issued to Leonard Sydenstricker on Jul. 7, 1992; and U.K. Pat. No. 471,730, issued on Sep. 3, 1937, to Alfred Reginald Shepherd.
Eckman '739 illustrates staged energization of electrical heating elements, a step-down control circuit transformer, and a high temperature cutout switch.
Control of electric power by a flow switch, and water heaters sufficiently compact to be built into a building wall or interior partition are taught in Malzoni et al. '789, Todd, Jr. '350, and the U.K. reference '730. The flow switch disclosed in the U.K. reference includes a plunger displaced by water flow.
It is known to employ solid state switches to control electrical current to the heating elements. Examples are seen in Davidson '515 and Dytch et al . '147. The latter reference teaches mounting solid state switches on a wall of the heating chamber, thereby recovering heat generated by these switches. This reference also teaches locating a temperature sensor at the outlet of the heater.
Further location of electrical components on a flat heating chamber wall is shown in Knight '465, wherein disc type switches are featured.
The use of triacs as switches, and control of the triacs by optotriacs is shown in Davidson '515 and Eddas '127.
Sydenstricker '034 discloses a pressure control valve, a one-way check valve, a pressure relief valve, and pressure initiated heating control.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.